Electronic and Structural Properties of SCSb and Sc Punder High Pressure

In the present study, the Full-Potential Linearized Augmented Plane Wave method that depends on the Density Functional Theory was used to investigate the structural phase transformations of ScSb and ScP compounds under high pressure. In these calculations, the local density approximation (LDA) and the gradient generalized approximation (GGA) for the exchange correlation potential have been used . For ScSb the equations of state (EOS's) of rock- salt(RS), cesium chloride(CsCl), zincblende(ZB) and wurtzite(WZ) have been calculated, from these (EOS's), it is found that a transition under high pressure is occurred from rock salt structure to cesium chloride structure. The transition pressure and the structural properties have also been calculated, the energy band gap for all phases of ScSb have been calculated and (-0.873,-0.683, 1.434, 1.481) eV band gaps were found and indicating that ScSb is semimetals and semiconductors respectively. The same work was done for ScP using the same method. A number of transition phases are predicted for ScP ; rocksalt to cesium chloride and wrutzite to zincblende. The transition pressure for each case was calculated. The structural properties have also been calculated, Finally the energy band gap for each phase was investigated. (-0.787,-0.583, 1.578, 1.6249)eV energy band gaps are found, which means that ScP behaves as metal, semimetal and semiconductor respectively. The most important results of this study are: 1.the structural parameters agree very well with the available experimental data and the other theoretical calculations. 2.the transition from structure to another is possible under high pressure, for ScSb the transition pressure from rocksalt to cesium chloride was found to be (31.5)GPa by LDA method and 35.4 GPa by GGA method. 3.For ScP the transition pressure from rocksalt to cesium chloride was found to be 69 GPa and from wurtzite to zincblende was found to be 84GPa by LDA method, while the transition pressure from rocksalt to cesium chloride was found to be 73.4 GPa and from wurtzite to zincblende was found to be 88 GPa by GGA method . 4.ScSb behaves as semimetal for rocksalt, metal for cesium chloride and semiconductor for zincblende and wurtzite phases using both LDA and GGA methods. 5.ScP behaves as semimetal for rocksalt, metal for cesium chloride and semiconductor for zincblende and wurtzite phases using both LDA and GGA methods. 6.Rocksalt was found to be the ground state for ScSb and ScP compound at ambient conditions.